J2EE|servletè????¤??¨ DB|&

servletè???¤?¨
1. Servletè???¤?¨?o??
Servletè???¤?¨?ˉServlet????§?1???¨?3?????è|?¨?￥??????oé?¨??????ˉ?|??? ?è???¤???¤?-?¨?·???é????-?-?Servletè???¤?¨?é?¨?o???
A??è?¤èˉè???¤
B??????????? ?è???¤
C?????è???￠è???¤
D???°??????è???¤
E??? ?ˉè???¤
F????¤?è???¤
G??èμ?oè??é?è§|??o???è???¤
Servletè???¤?¨?￥?￡?????
???Servletè???¤?¨?±?é???é?????°javax.servlet.Filter?￥?￡?è???a?￥?￡???3??aè???¤?¨?±???é?????°??1?3??
?1?3 èˉ′?
init(FilterConfig cfg) è??ˉServletè???¤?¨???§??1?3???§è′¨?-???servlet?init?1?3?
doFilter(ServletRequest,ServletResponse,FilterChain) ?????é?è???¤???????èˉ·?±è??é?è???¤?¨?3è?URL????Servlet??1?¨?°?è°?¨è???¤?¨?doFilter?1?3?FilterChain??°?¨?oè??é????-è???¤?¨
destroy() Servlet??1?¨?¨é?ˉè???¤?¨?????è°?¨èˉ￥?1?3??è???a?1?3??-?ˉ??￥é??Servletè???¤?¨? ?¨?èμ?o??§è′¨?-???servlet?destory()?1?3?
Servletè???¤?¨????o?-￥éa¤??
A?????°javax.servlet.Filter?￥?￡?servlet?±?
B?????°init?1?3??èˉ??è???¤?¨???§????°
C?????°doFilter?1?3??????ˉ1èˉ·?±?è???¤???o
D??è°?¨FilterChain?￥?￡?ˉ1è±??doFilter?1?3??????-?è???¤?¨?? éèˉ·?±???o
F.?¨web.xml??-é???Filter
2.????¨è???¤?¨?¤???-?é?é￠
???¨?¨?·??éé?μé￠è??￥???·?????|?è??￥?ˉ??-?????°servlet????è??oè???a???1?????ˉè??°±???ˉ?1±? ??è??ˉ? ??oserlvet??-é?è?¤?ˉ??￥ISO-8859-1? ?????? ????|???°??¤??aServlet,?¤??a??°??è?? ·?°±???é??è???aé?é￠???????ˉ??￥éè?????aè???¤?¨????è§￡?3???????°?è??oè??oé??ˉ???-????°ISO-8859-1è??? ??oGBK?é￡??μ??￡? ??
3.????¨è???¤?¨è?¤èˉ?¨?·??
?ˉ??aè???¤?¨?1?ˉ??￥é?????§???°???ˉ??￥?°??éè|è???¤??°?é????°è???aFilter?é?????°??-??è???¤?????|?èˉ·?±?°??¨é?????°??-?????è???è?? · ?°±é???o?¨?¨?o??-?????? ??ˉ??aFilter??-??§?????é??ˉ??￥???°é????ˉ1è±????¨Filter??-é????o??a??éè|è???¤??°???????a?ˉ??éé?μé￠??????a?ˉ?§è???é è?¤èˉ?servlet??
4.Servlet????¨
?±??????Swing?é￠?o?¨?????Servlet?1?ˉ??￥???o????¨????￥?ˉ1Servlet??1?¨???Servlet??-??￥è±???o?????o??o?Servlet????¨???è|???￥??? ?§??
ServletRequestListener ,ServletRequestAttributeListener??
HttpSessionActivationListener ,HttpSessionBindingListener ,
HttpSessionAttributeListener,HttpSessionListener,
ServletContextListener?-?-?
è??o????¨???è|?¨?￥???session,request,applicationè?????a?ˉ1è±?é?-??°??????
----------------------------------------------------------------------------------------------------------------

servlet API??-?éè|?????a?è??°±?ˉè??¤??oservlet?JSPé?μé￠???1è???¤?¨?è???¤?¨????o??o???????¨??ˉ??é? ?“servleté??￥”????§?è???o?¤§??? ??????￡??

è???¤?¨?ˉ????a?¨?o??????o???1???3?servlet?JSPé?μé￠è?è??¨????¨???è???¤?¨?ˉé? ?°????a??¤??aservlet?JSPé?μé￠?????1????ˉ??￥?￡?￥è??￥è??oèμ?o?èˉ·?±????ˉ??¨è??1???è???¤?¨?ˉ??￥???|???é????

1. ??￥???è§??1??è°?¨èμ?o???3??è°?¨servlet?JSPé?μé￠???

2.???¨????1è??èˉ·?±????ˉè°?¨èμ?o?

3. è°?¨èμ?o?????¨?é??o?°??￠?·?o??ˉ1??è?è?????1

4. é??-￠èˉ￥èμ?oè°?¨????￡?1??￥è???°?????èμ?o??è??????a?1????????￡? ??????￠è??o?
è???¤?¨????o? ??aéè|?￥??¤ ??

é|???????￥???§?¨??????ˉé?¨??1???°è￡???±?è???o??? ?30??a????serlvet?JSPé?μé￠??éè|?????????????1??￥??°??è????é′????2?é?é￠???é ????a????è???¤?¨??????°???o?¨?°30??aèμ?o???3?ˉ?

??????????¨??è??¤?°é??o§è??é??3?-??è?¨?°??￡? ????|??è??ˉ1?oJSP?1?????·????????-??è?????°? ?1?′??aé?μé￠é??-?¨è?¨?°????è???ˉé??-?¨????é?è???????|???? ?é????￥èa??o???1?è??é?è???¨????1?é?μé￠??è??oé?μé￠??°è??é?é????????2?é?é￠????o??????aè??é?é??è???¤?¨?1?????o?¨?°?3è|é??è??é??é?μé￠???3?ˉ?

????è???¤?¨????? è??¤?ˉ1è???¤????èμ?oè?è??1é?§??′?1??? ?è???¤?°?-èμ?o??è??oèμ?oé¤?o?????è|?′?1?¤?????????????è???°?1???2?é?é￠???é ????a??2???￠è???¤?¨???aè|?é?°±????¨???

??è|?3¨???è???¤?¨?a?¨??servletè§è2.3?????1?????¨??????¨??|??? ?Web?o?¨éè|?ˉ??§?????¨???°±??è?????¨è???¤?¨?

1????o???o??è???¤?¨

??o??????aè???¤?¨???????o??a?-￥éa¤??
1????o??????a???°Filter?￥?￡??±??è???a?±?éè|????a?1?3??????ˉ??doFilter?init?destroy?
doFilter?1?3??????è|?è???¤??￡? ??è§???2?-￥????init?1?3??o??è??????????èdestroy?1?3è?è????￥?

2???¨doFilter?1?3??-???￥è???¤è???o?doFilter?1?3????????a??°??oServletRequest?ˉ1è±???-¤?ˉ1è±???è???¤?¨????o?ˉ1è??￥?????ˉ ?????è?¨??°???cookie?HTTPèˉ·?±?¤′??????¨è??é??????o??a??°??oServletResponse??é????¨????è???¤?¨??-????￥?-¤??°???????a? ?°??oFilterChain???|?????-￥?è?°???-¤??°?¨?￥è°?¨servlet?JSPé?μ?

3??è°?¨FilterChain?ˉ1è±??doFilter?1?3?Filter?￥?￡?doFilter?1?3?????aFilterChain?ˉ1è±?????o???????a? ?°??¨è°?¨?-¤?ˉ1è±??doFilter?1?3???????′???????a???3?è???¤?¨??|??2???|????aè???¤?¨??servlet?JSPé?μé￠?3è???servlet?JSP é?μé￠è￠????′??

4???ˉ1???o?servlet?JSPé?μé￠?3¨?è???¤?¨??¨é¨??2?è?°??|??????web.xml????-????¨filter?filter-mapping??′ ?

5???|?¨???′??¨servlet?é2?-￠?¨?·???¨??o?servlet URL??è?è???¤?¨è??????

1.1??o??????a???°Filter?￥?￡??±?
??è???¤?¨é???é?????°javax.servlet.Filter?è???a?￥?￡???????a?1?3???????odoFilter?init?destroy?

public void doFilter(ServletRequset request,
ServletResponse response,
FilterChain chain)
thows ServletException, IOException

?ˉ??è°?¨????aè???¤?¨???3???ˉ???èˉ·?±???-¤è???¤?¨???3?servlet?JSPé?μé￠???????°±?§è???doFilter?1?3??-￡?ˉè???a?1?3????o?¤§é¨?è???¤é?è?? ???????a??°??o???? ?￥èˉ·?±??3?ServletRequest??ˉ1?o????è???¤?¨???¤§?¤?°è???¤é?è??ˉ?o?oè???a?ˉ1è±????|??¤?HTTPèˉ·?±???1???éè|è??é?èˉ? ?|getHeader?getCookies?-?¨ServletRequest??-? ?3???°??1?3???°±è|??-¤?ˉ1è±??é ? HttpServletRequest?

????o??a??°??oServletResponse?é¤?o?¨??¤??a???￠??è|????¨????￥?¤??é???????￥è???a??°?é|????|???????¨é????ˉ1???3servlet?JSPé?μ é￠?è??é???ˉè°?¨response.getWriter?1??′?￥?é????a??o?°??￠?·?o?????????|????????1???3?servlet?JSPé?μé￠?è??o???ˉ?? ?o????¨????a??é???é?°???è??o??ˉ1è±???-???????¨è°?¨serlvet?JSPé?μé￠???è???¤?¨?ˉ?￡?￥è??o???|??é?°±????1?????1??é?°??￠?·?o?

DoFilter???????a??°??oFilterChain?ˉ1è±???ˉ1?-¤?ˉ1è±?è°?¨doFilter??￥???′???servlet?JSPé?μé￠???3???????aè???¤?¨??|??2???|????a???3?è???¤?¨????ˉ1doFilter?è°?¨???′?servlet?JSP??èo??

public void init(FilterConfig config)thows ServletException

init?1?3?a?¨?-¤è???¤?¨??????????§????§è??????ˉ?ˉ???è°?¨è???¤?¨é??§è?????ˉ1?o????è???¤?¨???ˉ????-¤?1?3?????a??o?????????¤??a?? éè|????¨init? é|???FilterConfig?ˉ1è±?????ˉ1servlet?ˉ?￠?web.xml??????-??′??è???¤?¨??è??é??? ?-¤????é???3?ˉ???¨init?° FilterConfig?ˉ1è±??-???¨????a?-??μ??-????￥???doFilter?1?3è??¤è??é?servlet?ˉ?￠?è???¤?¨?.???????FilterConfig?ˉ1è±??· ?????agetInitParameter?1?3????è??¤è??é?é¨??2?è?°??|??????web.xml????-?é?è???¤?¨??§???°?

public void destroy( )
?¤§?¤?°è???¤?¨????°??o?-¤?1?3???????a??o??????è????ˉ???¨???￥???èˉ??|?3é-è???¤?¨????¨???????°???oè??￥?± ?-??é¤??????

1.2?°è???¤è???o???￥doFilter?1?3
doFilter?1?3??o?¤§?¤?°è???¤?¨?°?3é?é¨???ˉ??è°?¨????aè???¤?¨????é?è|?§è?doFilter??ˉ1?o?¤§?¤?°è???¤?¨?￥èˉ′??doFilter?§è???-￥éa¤?ˉ ?o?o?? ?￥?????ˉ??? ?-¤???ˉè?è|???¨????odoFilter????????a??°????ServletRequest?è???a?ˉ1è±????????é ??o HttpServletRequest?±??????￥????ˉ1èˉ￥?±???′?1???1?3?è??é??

1.3è°?¨FilterChain?ˉ1è±??doFilter?1?3
Filter?￥?￡?doFilter?1?3??￥????aFilterChain?ˉ1è±?????o??????????a??°??¨è°?¨èˉ￥?ˉ1è±??doFilter?1?3???????′???????a???3? è???¤?¨?è???aè??¨??è????-?°é???-??????aè???¤?¨??o?-￠??¨??????aè???¤?¨è°?¨??FilterChain?ˉ1è±??doFilter?1?3???????′?servlet? é?μé￠èaèo??
???ˉ??é???-?????è???¤?¨é??ˉ??￥éè???è°?¨??FilterChain?doFilter?1?3??-?-è???aè??¨??¨è?? ·???μ???????è°?¨JSPé?μé￠?serlvet???1?????-?-?-¤è°?¨è??¨?è???¤?¨è′è′￡?°è??o???????￠?·?o?

1.4?ˉ1é???servlet?JSPé?μé￠?3¨?è???¤?¨
é¨??2?è?°??|?????2.3??????￥?o??¤??a?¨?oè???¤?¨???′ ??????ˉ??filter?filter-mapping?filter??′ ??3????3¨?????aè???¤?ˉ1è±???filter-mapping??′ ???èˉ￥è???¤?ˉ1è±???o?¨?URL?

1.filter??′
filter??′ ???oé¨??2?è?°??|??????web.xml????é¨????filter-mapping?servlet?servlet-mapping??′ ?1??filter??′ ?·??|???-??a?ˉè???-??′ ??

1? iconè??ˉ????a?ˉé???′ ?????￡°?IDEè??¤????¨?????a??è±??????
2?filter-nameè??ˉ????a??é???′ ??????è???¤?¨?é????aé?????-?
3?display-nameè??ˉ????a?ˉé???′ ???????oIDE????¨??-??§°?
4? descriptionè??1?ˉ????a?ˉé???′ ???????oIDE?????ˉ???????????￡?
5? filter-classè??ˉ????a??é???′ ???????è???¤?¨???°?±?????¨é????
6? init-paramè??ˉ????a?ˉé???′ ???????1?ˉ???¨FilterConfig?getInitParameter?1?3èˉ?????§???°????aè???¤?¨??′ ?ˉ????¤??ainit-param??′ ?

èˉ·?3¨???è???¤?ˉ?¨serlvetè§è2.3???-???????￥??? ?-¤??web.xml??????é??????¨DTD?2.3??????é￠????????a???????-??
<xml version="1.0" encoding="ISO-8859-1"?>
DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">

MyFilterfilter-name>
myPackage.FilterClassfilter-class>
filter>

...filter-mapping>
<web-app>

2.filter-mapping??′
filter-mapping??′ ???oweb.xml??????-filter??′ ?1?serlvet??′ ?1????????|??????a?ˉè???-??′ ??

1? filter-nameè???a??é???′ ??é?????¨filter??′ ?￡°??????oè???¤?¨???§°???1é?

2? url-pattern?-¤??′ ?￡°?????a??￥?? ??/?????§??¨??????????è???¤?¨?o?¨?URL???filter-mapping??′ ??-??é?????url-pattern? servlet-name?????è??ˉ1???afilter-mapping??′ ????¤??aurl-pattern??′ é?1??|????è???¤?¨é?¨?o?¤??a?¨??????ˉé?¤ ?′??afilter-mapping??′ ?

3? servlet-name?-¤??′ ???o????a??§°???-¤??§°??é???????¨servlet??′ ???oservlet?JSPé?μé￠???§°???1é???è??????afilter-mapping??′ ??? ?¤??aservlet-name??′ é?1??|????è???¤?¨é??o?¤??aservlet????ˉé?¤è???afilter-mapping??′ ?
??é￠???????a???-??
xml version="1.0" encoding="ISO-8859-1"?>
DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">

MyFilterfilter-name>
myPackage.FilterClassfilter-class>
filter>

MyFilterfilter-name>
/someDirectory/SomePage.jspurl-pattern>
filter-mapping>
web-app>

1.5?|?¨???′??¨servlet
?¨?ˉ1èμ?o?o?¨è???¤?¨?????ˉéè????è|?o?¨è???¤?¨?URL?¨????servlet??￥?????|????servlet?????-¤??§°??é????web.xml? servlet??′ ??-???o???§°???1é??|?????¨?o?¨?°????aserlvet?URL?¨???????-¤?¨?????é???????¨web.xml???′ servlet- mapping?????¨??????1é????ˉ???¤?°????¨????¨“???′??¨servlet”??oservlet????????a??o??URL??http: //host/WebAppPrefix/servlet/ServletName?éè|??èˉ?¨?·?????¨è???aURLè??é?servlet??è?? ·????è?è???¤?¨ è????????
???|????|???¨filter?filter-mapping??¤o???oSomeFilter?è???¤?¨?o?¨?°???oSomeServlet?servlet????|????

SomeFilterfilter-name>
somePackage.SomeFilterClassfilter-class>
<filter>

SomeFilterfilter-name>
SomeServletservlet-name>
<filter-mapping>

?￥????¨servlet?servlet-mappingè§??URLhttp://host/webAppPrefix/Blah ?oèˉ￥è°?¨SomeSerlvet???|????¤o??

SomeFilterfilter-name>
somePackage.SomeFilterClassfilter-class>
filter>

SomeFilterfilter-name>
>/Blahservlet-name>
<filter-mapping>

?°?¨???¨??￠?·?o????¨URLhttp://host/webAppPrefix/Blah ???°±??è°?¨è???¤?¨?è???¤?¨???o?¨?°
http://host/webAppPrefix/servlet/SomePackage.SomeServletClass?
?°??????3é-???′??¨?????¨???¨?1?3????ˉ???ˉ?§??¤???o??1?3??é?°? ?°Web?o?¨é?/servlet?¨?????è?? ·?????????-¤?¨????èˉ·?±è￠?é?°???? servlet??-???o?oé?°? ?°?-¤?¨?????é|??oèˉ￥??o??????a????servlet??????°????éèˉˉ???ˉ???é????¨?·?°é???±é?μ??????????¨servlet? servlet-mapping??′ ?é???/servlet?¨????èˉ·?±?°èˉ￥servlet??¨?o???9-1???o?o????a???-????-?

?¨?o???9-1 web.xml??é?????o?servlet URL??????
xml version="1.0" encoding="ISO-8859-1"?>
DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd">

Errorservlet-name>
somePackage.ErrorServletservlet-class>
servlet>

Errorservlet-name>
/servlet/*url-pattern>
servlet-mapping>

<web-app>
-------------------------------------------------------------------------------------------
è§￡?3?1±?

web.xml? é???

Filter

com.util.EncodingFilter

Encoding
gb2312

Filter
/*

EncodingFilter.java
【J2EE|servletè????¤??¨】package com.hibernate.util;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
public class EncodingFilter implements Filter {
protected FilterConfig config;
protected String Encoding = null;
public void init(FilterConfig config) throws ServletException {
this.config = config;
this.Encoding = config.getInitParameter("Encoding");
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
if (request.getCharacterEncoding() == null) {
if (Encoding != null) {
request.setCharacterEncoding(Encoding);
response.setCharacterEncoding(Encoding);
}
}
chain.doFilter(request,response);
}
public void destroy() {}
}
OK!!!
----------------------------------------------------------------------------------------------------

??????è???¤?¨???°±?ˉ??o?oè?°??????aurl?èˉ·?±??é′ filter:

package com.javaeye.wqf;
import javax.servlet.*;
public class CounterFilter implements Filter {
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
long start = System.currentTimeMillis();
System.out.println("Filter start at "+start);
chain.doFilter(request, response);
long end = System.currentTimeMillis();
System.out.println("Filter end at "+end);
}
}

test
com.javaeye.wqf.CounterFilter
test
/*

??è???μ???ˉ?2????1é?é￠?????ˉ?????è??????a?¨????¤§?????????è·3?o???è?¤?a?￡???|?é????ˉcancel??
?°±????°filter?1??2??è?????1?°±?ˉèˉ′

System.out.println("Filter end at "+end);

?1??2???§è?. ?? ?ˉ:

chain.doFilter(request, response);
?§è??°è?é??????è?éè°?¨?????filter?servlet?????￥è???aè°?¨?°???ˉ????a??é??è??¨?
?¨è???aè°?¨é???°?????¨éè?request?resonse?????è??￥?????/?é?°?????|?è??￥?o?°????????°?′?￥??1?oException
?? ???￡? é?2???è·??????????￥?|??o?°???????chain.doFilter?é￠??°±?????§è??
?ˉ??￥?chain.doFilter???°try finally?????-????èˉ???-??è￠??§è?